Heat exchanger

ABSTRACT

A heat exchanger  1 A has: two header pipes  2  and  3  arranged parallel at an interval; a plurality of flat tubes  4  arranged between the header pipes  2  and  3  with refrigerant passages  5  inside them communicating with the inside of the header pipes  2  and  3;  and corrugated fins  6  arranged between adjacent flat tubes  4.  To outward facing flat surfaces of, of the plurality of flat tubes  4 , those located outermost, outermost corrugated fins  6   a  having pleats in the shape of a louver are fitted.

TECHNICAL FIELD

The present invention relates to a parallel-flow-type heat exchanger.

BACKGROUND ART

Parallel-flow-type heat exchangers are widely used in car airconditioners, outdoor units of building air conditioners, etc. In theparallel-flow-type heat exchanges, a plurality of flat tubes arearranged between a plurality of header pipes with a plurality ofrefrigerant passages inside the flat tubes communicating with the insideof the header pipes and in which fins such as corrugated fins arearranged between the flat tubes.

An example of a conventional parallel-flow-type heat exchanger is shownin

FIG. 10. In FIG. 10, the vertical-direction positional relationship isconsistent with that in the real world. The heat exchanger 1 has twohorizontal header pipes 2 and 3 arranged parallel at an interval in thevertical direction, and has a plurality of vertical flat tubes 4arranged between the header pipes 2 and 3 with a predetermined pitch inthe horizontal direction. The flat tubes 4 are elongate members made byextrusion of metal, and have refrigerant passages 5 formed insidethrough which to circulate a refrigerant. The flat tubes 4 are arrangedwith their length direction—the extrusion direction—vertically aligned,and therefore the refrigerant circulation direction through therefrigerant passages 5 is vertical. A plurality of the refrigerantpassages 5 with an equal cross-sectional shape and an equalcross-sectional area are arranged in the depth direction in FIG. 10,giving the flat tubes 4 a harmonica-shaped horizontal cross section. Therefrigerant passages 5 each communicate with the inside of the headerpipes 2 and 3. Between adjacent flat tubes 4, corrugated fins 6 arearranged.

The header pipes 2 and 3, the flat tubes 4, and the corrugated fins 6are all formed of metal with good heat conduction, such as aluminum. Theflat tubes 4 are fixed to the header pipes 2 and 3 by brazing orwelding, and so are the corrugated fins 6 to the flat tubes 4.

The heat exchanger 1 shown in FIG. 10 is a so-called down-flow,parallel-flow-type heat exchanger. Between the upper and lower headerpipes 2 and 3, a large number of flat tubes 4 are arranged with theirlength direction vertically aligned and, between the flat tubes 4,corrugated fins 6 are arranged. The heat exchanger 1 thus has a largeheat dissipation (heat absorption) area and allows efficient heatexchange. At one end of the lower header pipe 3, a refrigerant port 7 isprovided; at one end of the upper header pipe 2 diagonal to therefrigerant port 7, a refrigerant port 8 is provided. It should beunderstood that the positional relationship between the refrigerantports 7 and 8 is merely one example and is in no way meant as alimitation. For example, the header pipe 2 may be provided withrefrigerant ports 8 one at each end.

In FIG. 10, solid-line arrows indicate the case where the heat exchanger1 is used as an evaporator, in which case the refrigerant flows inthrough the refrigerant port 7 of the lower header pipe 3 and flows outthrough the refrigerant port 8 of the upper header pipe 2. That is, therefrigerant flows from down upward. When the heat exchanger 1 is used asa condenser, the refrigerant flows in the opposite direction;specifically, as dotted-line arrows in FIG. 10 indicate, the refrigerantflows in through the refrigerant port 8 of the upper header pipe 2 andflows out through the refrigerant port 7 of the lower header pipe 3.That is, the refrigerant flows from up downward.

In the heat exchanger 1 of FIG. 10, the corrugated fins are arrangedonly between the flat tubes 4, and no corrugated fins are fitted to theoutward facing flat surfaces of, of the plurality of flat tubes 4, thoselocated outermost. These surfaces, however, are often fitted withcorrugated fins, and such examples are seen in Patent Literatures 1 to 3listed below.

The heat exchanger disclosed in Patent Literature 1 is aparallel-flow-type heat exchanger with flat tubes horizontally aligned,and has corrugated fins fitted on the outward facing flat surfaces ofthe outermost flat tubes as well. Here, side plates for protecting thefins are arranged at the outer ends of the outermost corrugated fins

The heat exchanger disclosed in Patent Literature 2 also is aparallel-flow-type heat exchanger with flat tubes horizontally aligned,and has corrugated fins fitted on the outward facing flat surfaces ofthe outermost flat tubes. Here, side plates for reinforcing the coreportion—the portion composed of flat tubes and corrugated fins arrangedalternately—are arranged at the outer ends of the outermost corrugatedfins.

The heat exchanger disclosed in Patent Literature 3 also is aparallel-flow-type heat exchanger with flat tubes horizontally aligned.Here, side sheets are brazed at the outer ends of corrugated fins atboth ends.

Citation List Patent Literature

[Patent Literature 1] JP-A-H05-79788

[Patent Literature 2] JP-A-2006-64194

[Patent Literature 3] JP-A-2007-139376

SUMMARY OF INVENTION Technical Problem

In a parallel-flow-type heat exchanger, certainly, fitting corrugatedfins to the outward facing flat surfaces of, of a plurality of flattubes, those located outermost increases the heat dissipation (heatabsorption) area and thus enhances the performance of the heatexchanger. However, if a trough part of a corrugated fin, i.e., a partof a corrugated fin where it is fixed to a flat tube, is hit by anobject with a sharp point, not only the corrugated fin but also the flattube may be damaged, possibly leading to leakage of the refrigerant. Forthis reason, in any conventional arrangement where corrugated fins arearranged also at such positions as described above, protective plates(such as the side palates or the side sheets in above-mentioned PatentLiteratures) are arranged, or a protective film is applied, further out(at the outer ends of those corrugated fins) to protect the flat tubes.Inconveniently, providing the protective plates or protective filmsaccordingly increases the number of components and hence the cost.

In view of the foregoing, an object of the present invention is, in aparallel-flow-type heat exchanger, when corrugated fins are fitted tothe outward facing flat surface of, of a plurality of flat tubes, thoselocated outermost, to eliminate the need to provide a protective plateor protective film further out.

Solution to Problem

To achieve the above object, according to the present invention, a heatexchanger has: a plurality of header pipes arranged parallel at aninterval; a plurality of flat tubes arranged between the plurality ofthe header pipes with refrigerant passages inside them communicatingwith the inside of the header pipes; a corrugated fin arranged betweenadjacent flat tubes; and outermost corrugated fins fitted to outerfacing flat surfaces of, of the plurality of flat tubes, those locatedoutermost, in which the outermost corrugated fins have adjacent pleatsoverlapped in the shape of a louver.

With this structure, even if an object with a sharp point comes close toan outermost corrugated fin, it is hard for it to penetrate through theoutermost corrugated fin because of the pleats overlapped in the shapeof a louver. Thus, the flat tubes can be sufficiently protected withoutproviding the protective plate (such as the side plate or the sidesheet) or protective film.

In the heat exchanger with the above-described structure, when theplurality of flat tubes are arranged with their length directionvertically aligned, it is preferable that the outermost corrugated finshave pleats extending obliquely downward.

With this structure, condensed water and defrost water adhered on theoutermost corrugated fins flow along the surfaces of the slanted pleatsdown to the tips of the pleats, and drip down from there; thus, it isless likely that water accumulates between the pleats of the outermostcorrugated fins and thereby blocks the flow of air.

In the heat exchanger with the above-described structure, it ispreferable that the plurality of flat tubes be arranged with theirlength direction horizontally aligned and, of the outermost corrugatedfins, at least the bottommost corrugated fin have adjacent pleatsoverlapped in the shape of a louver.

With this structure, when the parallel-flow-type heat exchanger is usedwith a side-flow arrangement, even if an object with a sharp point comesclose to the bottommost corrugated fin, it is hard for it to penetratethrough the bottommost corrugated fin because of the pleats overlappedin the shape of a louver. For this reason, even though the protectiveplate (such as the side plate or the side sheet) or protective film isdisused, it is possible to sufficiently protect the flat tube. Moreover,the condensed water and defrost water adhered on the outermostcorrugated fins flow along the surfaces of the slanted pleats down tothe tips of the pleats, and drip down from there; since they are notblocked by the protective plate or protective film, the drainage isimproved.

Advantageous Effects of Invention

According to the present invention, the outermost corrugated fins havethe shape of a louver, which makes it possible to protect the flat tubesto which they are fitted without relying on the protective plates andthe protective film. As a result, it is possible to omit the protectiveplates and the protective film and thereby reduce the component cost.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1] A vertical sectional view showing the outline of aparallel-flow-type heat exchanger according to a first embodiment of thepresent invention.

[FIG. 2] A vertical sectional view showing an outline of aparallel-flow-type heat exchanger according to a second embodiment.

[FIG. 3] An exploded perspective view of components of an airconditioner including the parallel-flow-type heat exchanger according tothe second embodiment.

[FIG. 4] A perspective view of a first fitting member used for thefitting of the parallel-flow-type heat exchanger according to the secondembodiment.

[FIG. 5] A perspective view of the first fitting member as seen from adifferent direction.

[FIG. 6] A perspective view of a second fitting member used for thefitting of the parallel-flow-type heat exchanger according to the secondembodiment.

[FIG. 7] A perspective view of the second fitting member as seen from adifferent direction.

[FIG. 8] A perspective view of a third fitting member used for thefitting of the parallel-flow-type heat exchanger according to the secondembodiment.

[FIG. 9] A perspective view of the third fitting member as seen from adifferent direction.

[FIG. 10] A vertical sectional view showing the outline of aconventional parallel-flow-type heat exchanger.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a first embodiment of the present invention will bedescribed with reference to FIG. 1. In FIG. 1, such components as findtheir counterparts in the conventional structure shown in FIG. 10 areidentified with common reference symbols, and no description of themwill be repeated.

A heat exchanger 1A according to the first embodiment is a down-flowtype;

header pipes 2 and 3 are horizontally aligned, and flat tubes 4 arearranged with their length direction vertically aligned. Outermostcorrugated fins 6 a are fitted to the outward facing flat surfaces of,of the plurality of flat tubes 4 lined up, those located outermost. Theoutermost corrugated fins 6 a are formed of metal with good heatconduction, such as aluminum. The corrugated fins 6 a are fixed to theflat tubes 4 by brazing or welding.

In FIG. 1, solid-line ^(arrows) indicate the case where the heatexchanger 1 is used as an evaporator, in which case a refrigerant flowsin through a refrigerant port 7 of the lower header pipe 3 and flows outthrough a refrigerant port 8 of the upper header pipe 2. That is, therefrigerant flows from down upward. When the heat exchanger 1 is used asa condenser, the refrigerant flows in the opposite direction;specifically, as dotted-line arrows in FIG. 1 indicate, the refrigerantflows in through the refrigerant port 8 of the upper header pipe 2 andflows out through the refrigerant port 7 of the lower header pipe 3.That is, the refrigerant flows from up downward.

Each of the outermost corrugated fins 6 a has pleats slanted in the samedirection as the length direction of the flat tubes 4, so that adjacentpleats overlap each other. Specifically, adjacent pleats overlap eachother in the shape of a louver. When the pleats are not slanted, thethickness of the outermost corrugated fin 6 a is, at the thinnest part,the thickness of a single material plate of the corrugated fin. Byslanting and overlapping the pleats, it is possible to minimize parthaving the thickness of a single material plate. In this way, even if anobject with a sharp point comes close to the outermost corrugated fin 6a from the side, it is likely that it makes contact with part where thepleats are overlapped. The object with a sharp point that has madecontact with the part where the pleats are overlapped is stopped by theoverlapping pleats; thus, the object is less likely to penetrate throughthe outermost corrugated fin 6 a. For this reason, components such asside plates and side sheets that have been required conventionally toprotect the outermost flat tubes 4 are no longer needed, and thus thecomponent cost can be reduced.

To form the outermost corrugated fin 6 a so as to have the shape of alouver, it is possible to either fit a corrugated fin that is previouslyformed to have such a shape to the flat tube 4, or fit a corrugated finhaving the same shape as the corrugated fins 6 between the flat tubes 4to the flat tube 4 and then topple the pleats in one direction, like indomino toppling, to slant.

As mentioned above, the heat exchanger 1A according to the firstembodiment is the down-flow type, and the flat tubes 4 are arranged withtheir length direction vertically aligned. The outermost corrugated fin6 a is fitted such that the pleats extend obliquely downward. In thisway, condensed water and defrost water adhered on the outermostcorrugated fin 6 a flow along the surfaces of the slanted pleats down tothe tips of the pleats and drip down from there; thus, it is less likelythat water accumulates between the pleats of the outermost corrugatedfin 6 a and thereby blocks the flow of air.

Next, a second embodiment of the invention will be described withreference to

FIGS. 2 to 9. A heat exchanger 1B according to a second embodiment is aside-flow type, in which header pipes 2 and 3 are aligned vertically andflat tubes 4 are arranged with their length direction horizontallyaligned. The refrigerant ports 7 and 8 are provided in the header pipe 3alone. Inside the header pipe 3, partition plates 9 a and 9 c areprovided at an interval in the vertical direction; inside the headerpipe 2, a partition plate 9 b is provided at a middle height of thepartition plates 9 a and 9 c.

When the heat exchanger 1B is used as an evaporator, a refrigerant flowsin through the refrigerant port 7 at the lower side as indicated by asolid-line arrow in FIG. 2. The refrigerant that has entered from therefrigerant port 7 is blocked by the partition plate 9 a and flowstoward the header pipe 2 via the flat tubes 4. The flow of therefrigerant is indicated by a leftward block arrow. The refrigerant thathas entered the header pipe 2 is then blocked by the partition plate 9 band flows toward the header pipe 3 via other flat tubes 4 The flow ofthe refrigerant is ^(indicated) by a rightward block arrow. Therefrigerant that has entered the header pipe 3 is then blocked by thepartition plate 9 c and flows toward the header pipe 2 again via stillother flat tubes 4. The flow of the refrigerant is indicated by aleftward block arrow. The refrigerant that has entered the header pipe 2then flows back to head toward the header pipe 3 again via still otherflat tubes 4. The flow of the refrigerant is indicated by a rightwardblock arrow. The refrigerant that has entered the header pipe 3 thenflows out through the refrigerant port 8. As described above, therefrigerant flows from down upward along a zigzag path. Although thenumber of partition plates is three here, it is merely one example, andthe number of partition plates and the resulting number of times therefrigerant flows back can be set arbitrarily as required.

When the heat exchanger 1B is used as a condenser, the refrigerant flowsin the opposite direction. Specifically, the refrigerant flows into theheader pipe 3 through the refrigerant port 8 as indicated by adotted-line arrow in FIG. 2, is then blocked by the partition plate 9 cand flows toward the header pipe 2 via the flat tubes 4, is then blockedby the partition plate 9 b in the header pipe 2 and flows toward theheader pipe 3 via other flat tubes 4, is then blocked by the partitionplate 9 a in the header pipe 3 and flows toward the header pipe 2 againvia still other flat tubes 4, then flows back at the header pipe 2 tohead toward the header pipe 3 again via still other flat tubes 4, andthen flows out through the refrigerant port 7, as indicated by adotted-line arrow; that is, the refrigerant flows from up downward alonga zigzag path.

Of the plurality of flat tubes 4, those located at the topmost and thebottommost are the outermost flat tubes 4; to their outward facing flatsurfaces, namely the top surface of the topmost flat tube 4 and thebottom surface of the bottommost flat tube 4, outermost corrugated fins6 a are fitted.

Of the two outermost corrugated fins 6 a at the top and bottom, at leastthe bottom one (the bottommost corrugated fin) has its pleats overlappedin the shape of a louver. In this way, even if an object with a sharppoint (for example, a screw) comes close to the bottommost corrugatedfin, it is hard for it to penetrate through the bottommost corrugatedfin because of the pleats overlapped in the shape of a louver. Thus, itis possible to sufficiently protect the flat tubes 4 even with theprotective plate (such as the side plate or the side sheet) disused.Moreover, the condensed water and defrost water adhered on thebottommost corrugated fin flow along the surfaces of the slanted pleatsdown to the tips of the pleats, and drip down from there; since they arenot blocked by the protective plate or protective film, the drainage isimproved.

Not only the bottommost corrugated fin but also the outermost corrugatedfin 6 a at the top (the topmost corrugated fin) may have adjacent pleatsoverlapped in the shape of a louver. In this way, even if an object witha sharp point comes close to the topmost corrugated fin, it is hard forit to penetrate through the topmost corrugated fin because of the pleatsoverlapped in the shape of a louver. Thus, it is possible tosufficiently protect the flat tubes 4 even with the protective plate(such as the side plate or the side sheet) disused. In FIG. 2, thetopmost corrugated fin also has the adjacent pleats overlapped in theshape of a louver.

FIGS. 3 to 9 show an example when a heat exchanger 1B according to asecond embodiment is assembled into an indoor unit of an airconditioner. Here, a core part of the heat exchanger 1B fondled of flattubes 4, corrugated fins 6, and outermost corrugated fins 6 a is bent tohave an L-shape as seen in a plan view.

In FIG. 3, other than the heat exchanger 1B, there are shown part ofcomponents composing a housing of the indoor unit of the air conditionerand fitting members for fitting the heat exchanger 1B to the housing.Specifically, 10 represents a base plate of the housing and 11represents one side plate of the housing, and these are formed bypressing a steel plate or by combining pressed steal-plate componentstogether.

The heat exchanger 1B is joined to the housing with three differentfitting members, all of which are synthetic resin components, and aplurality of screws that join the fitting members to the housing. Thefitting members are assembled to header pipes 2 and 3.

A top part of the header pipe 3 is sandwiched by a first fitting member12 having a shape as shown in FIGS. 4 and 5 and a second fitting member13 having a shape as shown in FIGS. 6 and 7. The first fitting member 12and the second fitting member 13 arc tightened with a screw 14 to be asingle piece. The first and the second fitting member 12 and 13 surrounda refrigerant port 8, and also serve to protect the joint of therefrigerant port 8.

A bottom part of the header pipe 3 is sandwiched by another pair of thefirst and the second fitting member 12 and 13. The posture of the firstand the second fitting member 12 and 13 on this side is inverted, in thevertical direction, from that of the first and the second fitting member12 and 13 surrounding the top part of the header pipe 3. The first andthe second fitting member 12 and 13 on this side are tightened with ascrew 14 to be a single piece. The first and the second fitting member12 and 13 surround a refrigerant port 7, and also serve to protect thejoint of the refrigerant port 7.

The first and the second fitting member 12 and 13 fitted at the top andbottom parts of the header pipe 3 as described above are (as a singlepiece) fixed to the housing with another screw 14. This completes thefitting at the header pipe 3 side.

For the fitting at the header pipe 2 side, two pieces of a third fittingmember 15 are used. The third fitting members 15 having shapes as shownin FIGS. 8 and 9 are fitted into the top and bottom ends of the headerpipe 2, and the third fitting members 15 are then fixed to the housingwith screws 14. This completes the fitting at the header pipe 2 side.

As described above, by fitting the heat exchanger 1B to the housing byuse of the first, the second, and the third fitting member 12, 13, and15, all of which are synthetic resin components, it is possible to avoiddirect contact of the heat exchanger 1B with the housing. As a result,even though the heat exchanger 1B and the housing are formed ofdifferent kinds of metal, it is possible to prevent electrolyticcorrosion.

By structuring a parallel-flow-type heat exchanger according to thefirst embodiment or the second embodiment, it is possible to preventdeformation of the outermost corrugated fin (fin distortion) duringproduction and transportation. This makes it possible to preventimpaired appearance of the product.

Since the corrugated fins can be arranged at the outermost sides eventhough the side plates and the side sheets are disused, it is possibleto increase the heat dissipation area compared with the case where theside plates and the side sheets, and hence the outermost corrugatedfins, are disused.

When the parallel-flow heat exchanger is a side-flow type, if aprotective plate (such as a side plate or a side sheet) is at thebottommost part, water drainage from the corrugated fin is madedifficult, and thus water gradually accumulates and blocks the airpassing through the heat exchanger. When the bottommost corrugated finhas pleats overlapped in the shape of a louver and has no protectiveplate provided at its outer end, defrost water and condensed water flowdown without being blocked by the protective plate, and thus they do notblock the air passing through the heat exchanger.

It is to be understood that the present invention may be carried out inany other manner than specifically described above as embodiments, andmany modifications and variations are possible within the scope of thepresent invention. For example, it is not essential that the number ofthe refrigerant passages in the flat tube be two or more. The number ofthe refrigerant passages may be one.

INDUSTRIAL APPLICABILITY

The present invention finds wide application in parallel-flow-type heatexchangers.

LIST OF REFERENCE SYMBOLS

1A, 1B heat exchangers

2, 3 header pipes

4 flat tube

5 refrigerant passage

6 corrugated fin

6 a outermost corrugated fin

7, 8 refrigerant ports

1. A heat exchanger comprising: a plurality of header pipes arrangedparallel at an interval; a plurality of flat tubes arranged between theplurality of the header pipes with refrigerant passages inside themcommunicating with the inside of the header pipes; corrugated finsarranged between adjacent flat tubes; and outermost corrugated finsfitted to outward facing flat surfaces of, of the plurality of flattubes, those located outermost, wherein the outermost corrugated finshave pleats overlapped in a shape of a louver.
 2. The heat exchangeraccording to claim 1, wherein the plurality of flat tubes are arrangedwith a length direction thereof vertically aligned, and the outermostcorrugated fins have pleats extending obliquely downward.
 3. The heatexchanger according to claim 1, wherein the plurality of flat tubes arearranged with a length direction thereof horizontally aligned, and ofthe outermost corrugated fins, at least a bottommost corrugated fin hasadjacent pleats overlapped in a shape of a louver.